When I became ill in 1990 there were Environmental Illness doctors that I went to. Theron Randolph (deceased) and Dr. Rea (deceased). Dr. Rea's Environmental Health Center is still open in Dallas, TX. I have researched MCS or EI doctors today and cannot find one to go to. You know you have MCS when you begin reacting to things that never bothered you before. Your symptoms might be headaches, bloating, gas, trouble breathing, anxiety and many other symptoms. Going to an EI doctor confirms MCS by your symptoms. At Dr. Rea's clinic, they do a lot of allergy testing and allergy shots. I went to Dr. Rea's Clinic over 25 years ago so cannot comment on what they do now for MCS. As far as I know, there is nothing that can be done except staying away from the chemicals. I am still looking for an answer. Prozac and Klonopin helped me for a long period of time, but stopped working.
In the past three years since I became quite ill again, I am going to allergists/immunologists, neurologists, psychistrists, ENT's, Internists, GI doctors, and Functional Medicine doctors, but really none of them know how to help me. They want me to try many different pills for the migraines and IBS. The two functional medicine doctors, were extremely expensive, and helped me the least. They wanted me to take loads of supplements that I could not tolerate. I am still looking for doctors to help me. Maybe other people have had good luck with Functional Medicine doctors, but for me, they were not helpful. There are no tests that I know of for MCS.